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Numerical study of a guide-vane-augmented vertical darrieus tidal-currentturbine 预览
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作者 Zhen Liu Zhi-meng Wang +1 位作者 Hong-da Shi Heng-liang Qu 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第3期522-530,共9页
It is reported that the augmented vertical axis turbine (VAT) has a better operating performance. A guide-vane type augmentation is proposed in this study, with a simpler outline and a better adaptability to various d... It is reported that the augmented vertical axis turbine (VAT) has a better operating performance. A guide-vane type augmentation is proposed in this study, with a simpler outline and a better adaptability to various directions of the incident water flow, as compared to the duct-type diffuser. A 2?D numerical model based on the computational fluid dynamics software ANSYS-Fluent is established and validated by experimental data. It is found that the guide vanes could narrow the flow path together with the VAT rotor and increase the flow velocity around the blades. The fluctuation of the instantaneous torque output is significantly reduced by using the guide-vane stator. The numerical results indicate that a four blades setup is suitable for the stator and the chord length of the guide vane should be equal to that of the rotor blade. The gap between the stator and the rotor is suggested to be a quarter of the chord length of the rotor blades. The non-zero pitch angle of the guide vane is found to have negative effects on the torque and the power output. The averaged power and torque coefficients for three non-zero directional angles of the incident flow are approximately 30% lower than those for the zero-directional angle. 展开更多
关键词 Tidal current energy VERTICAL axis turbine AUGMENTED rotor GUIDE VANE numerical simulation
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Impacts of El Nino on the somatic condition of Humboldt squid based on the beak morphology 预览
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作者 HU Guanyu YU Wei +4 位作者 LI Bai HAN Dongyan CHEN Xinjun CHEN Yong LI Jianhua 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第4期1440-1448,共9页
The Humboldt squid Dosidicus gigas has a short life span, and environmental variability plays a significant role in regulating its population dynamics and distribution. An analysis of 1 096 samples of D. gigas collect... The Humboldt squid Dosidicus gigas has a short life span, and environmental variability plays a significant role in regulating its population dynamics and distribution. An analysis of 1 096 samples of D. gigas collected by the Chinese commercial fishing vessels during 2013, 2014, and 2016 off the Peruvian Exclusive Economic Zone, was conducted to evaluate the impacts of El Nino events on the somatic condition of D. gigas. This study indicates that the slopes of all beak variables in relation to mantle length (ML) for females were greater than those of males during 2013, 2014, and 2016, and slopes of the upper crest length and the lower rostrum length significantly differed between females and males in 2013 (P<0.05). Variation in the slopes for beak variables among years was studied;no significant difference was observed (ANCOVA, P>0.05). The Fulton's condition coefficients (K) of females and males in 2013 and 2014 were significantly greater than those in 2016 (P<0.01). The K values of females were greater than those of males in 2013, 2014, and 2016, and K values significantly differed between females and males in 2013. In normal years, the chlorophyll a (Chl a) concentration showed an N-shaped variability from January to December. However, in the El Nino period, it tended to weaken the upwelling coupled with warm and low Chl a concentration waters. We suggest that the poor somatic condition of D. gigas during the El Nino year was resulted from the low Chl a concentration in the waters, and the abundance of D. gigas would decrease due to the unfavourable environment and the lack of prey items in the El Nino year. 展开更多
关键词 El Nino event Dosidicus GIGAS SOMATIC CONDITION abundance BEAK MORPHOLOGY
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A novel method for internal wave monitoring based on expansion of the sound speed profile 预览
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作者 Ke Qu Fengqin Zhu Wenhua Song 《海洋学报:英文版》 SCIE CAS CSCD 2019年第4期183-189,共7页
For acoustic detection of internal waves,the core issue is to obtain the temporal and spatial distribution of the sound speed profile(SSP).In the inversion process,the SSP is usually expressed by a few parameters thro... For acoustic detection of internal waves,the core issue is to obtain the temporal and spatial distribution of the sound speed profile(SSP).In the inversion process,the SSP is usually expressed by a few parameters through expansion.However,information about internal waves may sometimes be hard to read directly from the inversion results.The aim of this paper is to characterize the internal waves directly though expansion coefficients.By deducing the dynamic equations of the internal waves,an orthogonal basis called the hydrodynamic normal modes(HNMs)can be extracted from a certain number of SSP samples.Unlike the existing widely used empirical orthogonal functions(EOFs),the HNMs have a more explicit physical meaning that is directly related to internal wave activity.The HNMs are then used to expand the SSP time series,and the expansion coefficients are derived.Eventually,information about internal waves can be read directly from the time derivative of the expansion coefficients of the first two modes.In this study,this method is applied to thermistor string profiles from the northern shelf of the South China Sea,where the SSP shows evident spatial and temporal variations due to internal waves.The results show that the SSP can be described approximately by the first two modes with adequate precision.The special oscillation structure of the time derivative of the expansion coefficients can be used to detect internal solitary waves.The expansion coefficients can also give information on internal solitary wave amplitude and width.According to theoretical and experimental analysis,it can be concluded that the internal waves monitoring method introduced in this paper is effective.The HNMs method is simple to apply and depends less on sample data than EOFs.It could be used as an efficient alternative to EOFs to expand the use of the SSP in highly variable areas,where internal waves are intensive. 展开更多
关键词 INTERNAL WAVES HYDRODYNAMIC normal MODES INTERNAL SOLITARY WAVES South China Sea
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Seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea 预览
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作者 Yongcan Zu Shuangwen Sun +4 位作者 Wei Zhao Peiliang Li Baochao Liu Yue Fang Azizan Abu Samah 《海洋学报:英文版》 SCIE CAS CSCD 2019年第4期29-38,共10页
The seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea are investigated using the latest eddy dataset and ARMOR3D data.Eddy-centric composites revea... The seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea are investigated using the latest eddy dataset and ARMOR3D data.Eddy-centric composites reveal that the horizontal distribution of temperature anomaly associated with eddy in winter is more of a dipole pattern in upper 50 m and tends to be centrosymmetric below 50 m,while in summer the distribution pattern is centrosymmetric in the entire water column.The horizontal distribution of eddy-induced salinity anomaly exhibits similar seasonal characteristics,except that the asymmetry of the salinity anomaly is weaker.The vertical distribution of temperature anomaly associated with eddy shows a monolayer structure,while the salinity anomaly demonstrates a triple-layer structure.Further analysis indicates that the vertical distribution of the anomalies is related to the vertical structure of background temperature and salinity fields,and the asymmetry of the anomalies in upper 50 m is mainly caused by the horizontal advection of background temperature and salinity. 展开更多
关键词 MESOSCALE EDDY THERMOHALINE structure SEASONAL CHARACTERISTICS South China Sea
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Numerical Study on Seasonal Transportation of the Suspended Sediments in the Modern Yellow River Mouth Effected by the Artificial Water and Sediment Regulation 预览
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作者 WANG Nan QIAO Lulu +5 位作者 LI Guangxue ZHONG Yi SONG Dehai DING Dong GAO Fei JI Fengying 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第1期20-30,共11页
Since 2002,an artificial water and sediment regulation(AWSR)has been carried out,which largely reduced water and sediment discharged from the Yellow River into the Bohai Sea.Although the sediment transport in the Yell... Since 2002,an artificial water and sediment regulation(AWSR)has been carried out,which largely reduced water and sediment discharged from the Yellow River into the Bohai Sea.Although the sediment transport in the Yellow River Mouth(YRM)has been observed and modeled intensively since AWSR,but preferentially for the non-storm conditions.In this study,a three-dimensional current-wave-sediment coupled model,DHI-MIKE numerical model,was used to examine the seasonal suspended-sediment transport in the YRM after the AWSR.Results show that the seasonal distribution of suspended-sediments in the YRM is dominated by wind and wave rather than river input.The major transport pathway of suspended-sediments is from the western Laizhou Bay to the Bohai Strait during the winter monsoon,especially in storm events.In addition,about 66%of the river sediments deposit within 30km of the YRM,which is smaller than previous estimations.It suggests that the YRM has been eroded in recent decades. 展开更多
关键词 YELLOW River MOUTH artificial water and SEDIMENT regulation MIKE suspended-sediment transport SEASONAL variation
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Wave parameters retrieval for dual-polarization C-band synthetic aperture radar using a theoretical-based algorithm under cyclonic conditions 预览
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作者 Yingying Ding Juncheng Zuo +5 位作者 Weizeng Shao Jian Shi Xinzhe Yuan Jian Sun Jiachen Hu Xiaofeng Li 《海洋学报:英文版》 SCIE CAS CSCD 2019年第5期21-31,共11页
Theoretical-based ocean wave retrieval algorithms are applied by inverting a synthetic aperture radar(SAR)intensity spectrum into a wave spectrum,that has been developed based on a SAR wave mapping mechanism.In our pr... Theoretical-based ocean wave retrieval algorithms are applied by inverting a synthetic aperture radar(SAR)intensity spectrum into a wave spectrum,that has been developed based on a SAR wave mapping mechanism.In our previous studies,it was shown that the wave retrieval algorithm,named the parameterized first-guess spectrum method(PFSM),works for C-band and X-band SAR at low to moderate sea states.In this work,we investigate the performance of the PFSM algorithm when it is applied for dual-polarization c-band sentinel-1(S-1)SAR acquired in extra wide-swath(EW)and interferometric wide-swath(IW)mode under cyclonic conditions.Strong winds are retrieved from six vertical-horizontal(VH)polarization S-1 SAR images using the c-band crosspolarization coupled-parameters ocean(C-3PO)model and then wave parameters are obtained from the image at the vertical-vertical(VV)polarization channel.significant wave height(SWH)and mean wave period(MWP)are compared with simulations from the WAVEWATCH-III(WW3)model.The validation shows a 0.69 m root mean square error(RMSE)of SWH with a–0.01 m bias and a 0.62 s RMSE of MWP with a–0.17 s bias.Although the PFSM algorithm relies on a good quality SAR spectrum,this study confirms the applicability for wave retrieval from an S-1 SAR image.Moreover,it is found that the retrieved results have less accuracy on the right sector of cyclone eyes where swell directly affects strong wind-sea,while the PFSM algorithm works well on the left and rear sectors of cyclone eyes where the interaction of wind-sea and swell is relatively poor. 展开更多
关键词 WAVE parameters synthetic APERTURE RADAR cyclonic condition
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Determination of water level design for an estuarine city 预览
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作者 CHEN Baiyu LIU Guilin +2 位作者 WANG Liping ZHANG Kuangyuan ZHANG Shuaifang 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第4期1186-1196,共11页
Based on the extreme value theory, self-affinity, and scale invariance, we studied the temporal and spatial relationship and the variation of water level and established a model of Gumbel-Pareto distribution for desig... Based on the extreme value theory, self-affinity, and scale invariance, we studied the temporal and spatial relationship and the variation of water level and established a model of Gumbel-Pareto distribution for designed flood calculation. The model includes the previous extreme value models, the over-threshold data, and the fractal features shared by previous extreme value models. The model was simplified into a logarithmic normal distribution and a Pareto distribution for specific parameter values, and was used to calculate the designed flood values for the Shanghai Wusong Station in 100- and 1 000-year return periods. The calculated results show that the value of the designed flood height calculated in the Gumbel-Pareto distribution is between those in the Gumbel and Pearson-Ⅲ distributions. The designed flood values in the 100- and 1 000-year return periods of the model were 0.03% and 0.11% lower, respectively, than the Gumbel distribution and 0.06% and 1.54% higher, respectively, than the Pearson-Ⅲ distribution. Compared to the traditional model based solely on extreme probability, the Gumbel-Pareto distribution model could better describe the probabilistic characteristics of extreme marine elements and better use the data. 展开更多
关键词 self-affinity SCALE INVARIANCE EXTREME VALUE distribution
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Wave height statistical characteristic analysis 预览
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作者 LIU Guilin CHEN Baiyu +3 位作者 WANG Liping ZHANG Shuaifang ZHANG Kuangyuan LEI Xi 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第2期448-460,共13页
When exploring the temporal and spatial change law of ocean environment, the most common method used is using smaller-scale observed data to derive the change law for a larger-scale system. For instance, using 30-year... When exploring the temporal and spatial change law of ocean environment, the most common method used is using smaller-scale observed data to derive the change law for a larger-scale system. For instance, using 30-year observation data to derive 100-year return period design wave height. Therefore, the study of inherent self-similarity in ocean hydrological elements becomes increasingly important to the study of multi-year return period design wave height derivation. In this paper, we introduced multifractal to analyze the statistical characteristics of wave height series data observed from oceanic hydrological station. An improvement is made to address the existing problems of the multifractal detrended fluctuation analysis (MF-DFA) method, where trend function showed a discontinuity between intervals. The improved MFDFA method is based on signal mode decomposition, replacing piecewise polynomial fitting used in the original method. We applied the proposed method to the wave height data collected at Chaolian Island, Shandong, China, from 1963 to 1989 and was able to conclude the wave height sequence presented weak multi-fractality. This result provided strong support to the past research on the derivation of multi-year return period design wave height with observed data. Moreover, the new method proposed in this paper also provides a new perspective to explore the intrinsic characteristic of data. 展开更多
关键词 wave HEIGHT PARTITION function MULTIFRACTAL spectrum MULTIFRACTAL detrended FLUCTUATION analysis (MF-DFA) signal mode DECOMPOSITION
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Domestication of marine microalga Nannochloropsis oceanica to freshwater medium and the physiological responses 预览
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作者 GUO Li LIANG Sijie +3 位作者 ZHANG Zhongyi LIU Hang WANG Songwen YANG Guanpin 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第4期1353-1362,共10页
Marine microalga Nannochloropsis oceanica LAMB0001 were domesticated (~730 generations,~two days each) to adapt freshwater BG11 medium. A number of freshwater medium adapted colony-derived strains were obtained. The s... Marine microalga Nannochloropsis oceanica LAMB0001 were domesticated (~730 generations,~two days each) to adapt freshwater BG11 medium. A number of freshwater medium adapted colony-derived strains were obtained. The strains were verified phylogenetically to be N. oceanica LAMB0001 based on the 18S ribosomal RNA gene. Freshwater-medium adapted strain (FA1) grew faster in the BG11 medium prepared with freshwater than wild-type N. oceanica grew in f/2 medium prepared with seawater. We assumed that (1) the expression patterns of the genes that expressed differentially between FA1 and the wild-type N. oceanica exposing to the BG11 medium (WT-F) have been reprogrammed;(2) the physiological processes in which these genes involved have been modified;and (3) a Gene Ontology (GO) term or a KEGG pathway enriched by DEGs between FA1 and WT-F has been up- or down-regulated if it was enriched simultaneously by up- or down-regulated DEGs between FA1 and WT-F, respectively. Under these assumptions, we found that FA1 reprogrammed the expression patterns of a set of genes that involved in cell adhesion, membrane and membrane integrity, material transportation, cell movement, and cellular signaling network. These changes in cellular functions and metabolic pathways indicate that the microalga modified its gene expression pattern in a wide function range and at a high regulation rank in order to adapt to the freshwater medium. It is feasible to domesticate marine microalgae to a freshwater habitat, which may aid to modify their cultivation performances. 展开更多
关键词 NANNOCHLOROPSIS oceanica DOMESTICATION ACCLIMATION ADAPTATION genetic variation
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The influence of slope collapse on water exchange between a pit lake and a heterogeneous aquifer
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作者 Bo Zhang Xilai Zheng +3 位作者 Tianyuan Zheng Jia Xin Shuai Sui Di Zhang 《中国环境科学与工程前沿:英文版》 SCIE EI CAS CSCD 2019年第2期63-71,共9页
Due to the increase in open pit mining,pit lakes have become common surface water features,posing a potential risk to subsurface aquifer.In this study,a pit lake–groundwater interaction model is built based on the ge... Due to the increase in open pit mining,pit lakes have become common surface water features,posing a potential risk to subsurface aquifer.In this study,a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package.For the first time,the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level.Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m3/a without collapse of the pit lake slope,while the total net water exchange under slope collapse conditions is 248000 m3/a(i.e.,a reduction of 1.40-fold).The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April,shifting to negative values in zone IV from June to August and in zone V in June and July.Moreover,the monthly net water exchange per unit width decreases from north to south,and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse. 展开更多
关键词 PIT LAK SLOPE COLLAPSE Groundwater-surface water INTERACTIONS NUMERICAL simulation
Responses of Yellow Sea Cold Water Mass to Typhoon Bolaven 预览
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作者 LI Jianchao LI Guangxue +4 位作者 XU Jishang QIAO Lulu MA Yanyan DING Dong LIU Shidong 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第1期31-42,共12页
A two-month seabed-mounted observation(YSG1 area)was carried out in the western Yellow Sea Cold Water Mass(YSCWM)using an RDI-300K acoustic Doppler current profiler(ADCP)placed at a water depth of 38 m in late summer,... A two-month seabed-mounted observation(YSG1 area)was carried out in the western Yellow Sea Cold Water Mass(YSCWM)using an RDI-300K acoustic Doppler current profiler(ADCP)placed at a water depth of 38 m in late summer,2012.On August 2012,Typhoon Bolaven passed east of YSG1 with a maximum wind speed of 20ms^-1.The water depth,bottom temperature,and profile current velocities(including u,v and w components)were measured,and the results showed that the typhoon could induce horizontal current with speed greater than 70cms?1 in the water column,which is especially rare at below 20 meters above bottom(mab).The deepening velocity shear layer had an intense shear velocity of around 10cms?1m?1,which indicated the deepening of the upper mixed layer.In the upper water column(above 20mab),westward de-tide current with velocity greater than 30cms?1 was generated with the typhoon’s onshore surge,and the direction of current movement shifted to become southward.In the lower water column,a possible pattern of eastward compensation current and delayed typhoon-driven current was demonstrated.During the typhoon,bottom temperature variation was changed into diurnal pattern because of the combined influence of typhoon and tidal current.The passage of Bolaven greatly intensified local sediment resuspension in the bottom layer.In addition,low-density particles constituted the suspended particulate matter(SPM)around 10 mab,which may be transported from the central South Yellow Sea by the typhoon.Overall,the intensive external force of the Typhoon Bolaven did not completely destroy the local thermocline,and most re-suspended sediments during the typhoon were restricted within the YSCWM. 展开更多
关键词 YELLOW Sea Cold Water Mass TYPHOON typhoon-driven current THERMOCLINE suspended PARTICULATE MATTER
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振荡浮子式双浮体波浪能装置的阵列特性 预览
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作者 纪仁玮 盛其虎 +3 位作者 王树齐 张玉全 张学伟 张亮 《船舶与海洋工程学报:英文版》 CSCD 2019年第3期325-333,共9页
As the energy supply problem worsens, the development and utilization of marine renewable energy have become a research hotspot. The development of wave energy is moving from the near shore to the distant sea. The pow... As the energy supply problem worsens, the development and utilization of marine renewable energy have become a research hotspot. The development of wave energy is moving from the near shore to the distant sea. The power-generation efficiency of a single two-floating-body wave-energy converter is relatively low. To fully utilize wave energy and improve the wave-energy capture rate of a fixed sea area, arranging a two-floating-body wave-energy converter array is necessary. This paper first introduces the basic theory of multi-floating flow field, time-domain calculation method, and influence factor of the waveenergy converter array. Then, the development of AQWA software in Fortran language considers the effect of power takeoff. A calculation method based on ANSYS–AQWA is proposed to simulate the motion of the oscillating-buoy two-floating-body wave-energy converter. The results are compared with the experimental results from the National Renewable Energy Laboratory. Finally, the ANSYS–AQWA method is used to study the power characteristics of simple and complex arrays of wave-energy converters. The average power generation of simple arrays is largest at 0°, and the average power generation of complex arrays does not change with the wave direction. Optimal layout spacing exists for the simple and complex arrays. These findings can serve as a valuable reference for the large-scale array layout of wave-energy converters in the future. 展开更多
关键词 OSCILLATING BUOY Two-floating body Wave-energy CONVERTER AQWA CONVERTER ARRAY Power characteristics
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Transcriptomic Response of Nannochloropsis oceanica to Benzo[a]pyrene 预览
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作者 ZHANG Zhongyi GUO Li +2 位作者 LIU Hang LIANG Sijie YANG Guanpin 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第3期680-686,共7页
In this study, the RNA sequencing was used to describe the response of Nannochloropsis oceanica, a marine microalga, to benzo[a]pyrene(BaP), a polycyclic aromatic hydrocarbon, in order to elucidate the metabolic pathw... In this study, the RNA sequencing was used to describe the response of Nannochloropsis oceanica, a marine microalga, to benzo[a]pyrene(BaP), a polycyclic aromatic hydrocarbon, in order to elucidate the metabolic pathways(or processes) involved in microalgal response to this stubborn pollutant. N. oceanica was exposed to BaP at a concentration of 90 μg L^-1 for 72 h, and its transcriptome was sequenced through the Illumina HiSeq^TM 2500 platform. This concentration of BaP was selected as it is the lowest for modeling the most appropriate growth inhibition of N. oceanica for transcriptomic analysis. We found that N. oceanica responds to BaP through degrading proteins and repairing DNA damaged by BaP. In addition, superoxide dismutase(SOD) strengthened its performance by increasing its transcript abundance. The physiological mechanism underlining the response of N. oceanica to BaP as revealed by transcriptomic analysis was consistent with the biochemical insights documented previously. 展开更多
关键词 NANNOCHLOROPSIS oceanica BENZO[A]PYRENE TRANSCRIPTOME PHYSIOLOGICAL RESPONSE
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Microbial diversity in Huguangyan Maar Lake of China revealed by high-throughput sequencing 预览
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作者 HOU Qinghua FANG Zhou +1 位作者 ZHU Qingmei DONG Hongpo 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第4期1245-1257,共13页
Huguangyan Maar Lake is a typical maar lake in the southeast of China. It is well preserved and not disturbed by anthropogenic activities. In this study, microbial community structures in sediment and water samples fr... Huguangyan Maar Lake is a typical maar lake in the southeast of China. It is well preserved and not disturbed by anthropogenic activities. In this study, microbial community structures in sediment and water samples from Huguangyan Maar Lake were investigated using a high-throughput sequencing method. We found significant differences between the microbial community compositions of the water and the sediment. The sediment samples contained more diverse Bacteria and Archaea than did the water samples. Actinobacteria, Betaproteobacteria, Cyanobacteria, and Deltaproteobacteria predominated in the water samples while Deltaproteobacteria, Anaerolineae, Nitrospira, and Dehalococcoidia were the major bacterial groups in the sediment. As for Archaea, Woesearchaeota (DHVEG-6), unclassified Archaea, and Deep Sea Euryarchaeotic Group were detected at higher abundances in the water, whereas the Miscellaneous Crenarchaeotic Group, Thermoplasmata, and Methanomicrobia were significantly more abundant in the sediment. Interactions between Bacteria and Archaea were common in both the water column and the sediment. The concentrations of major nutrients (NO^3-, PO4^3-, SiO3^2- and NH4^+) shaped the microbial population structures in the water. At the higher phylogenetic levels including phylum and class, many of the dominant groups were those that were also abundant in other lakes;however, novel microbial populations (unclassified) were often seen at the lower phylogenetic levels. Our study lays a foundation for examining microbial biogeochemical cycling in sequestered lakes or reservoirs. 展开更多
关键词 Huguangyan MAAR LAKE HIGH-THROUGHPUT SEQUENCING MICROBIAL diversity
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Theoretical Analysis of Bearing Capacity of Shallowly Embeded Rectangular Footing of Marine Structures 预览
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作者 ZHANG Qiyi WU Shaoxuan +1 位作者 WU Liangpeng LIU Zhijie 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第1期123-132,共10页
In this paper,the finite element analysis software ABAQUS is used to analyze the ultimate bearing capacity of three-dimensional rectangular footing of marine structures.The deformation law and the failure mode of homo... In this paper,the finite element analysis software ABAQUS is used to analyze the ultimate bearing capacity of three-dimensional rectangular footing of marine structures.The deformation law and the failure mode of homogeneous seabed soil beneath the rectangular footing are analyzed in detail.According to the equivalent plastic strain of soil under rectangular footing,an allowable velocity field of homogeneous seabed soil is reasonably constructed.Based on the plastic limit analysis theory of soil mass and by using the Mohr-Coulomb yield criterion,an upper bound solution of the ultimate bearing capacity of three-dimensional rectangular footing on general homogeneous seabed soil is derived,and a correction factor of ultimate bearing capacity of three-dimensional rectangular footing is given.To verify the rationality and applicability of this theoretical solution,some numerical solutions are achieved using the general-purpose FEM analysis package ABAQUS,and comparisons are made among the derived upper bound solution,the solution of Vesic,and the solution of Salgado et al.The results indicate that the upper bound solution of the three-dimensional shallowly embedded rectangular footing proposed in this paper is accurate in calculating the bearing capacity of homogeneous seabed soil.For undrained saturated clay foundation and sandy foundation with smaller internal friction angle,this upper bound solution can evaluate the ultimate bearing capacity of rectangular footing;with the gradual increase of the internal friction angle of the soil,the ultimate bearing capacity of the proposed upper bound solution is slightly higher than that of the rectangular footing. 展开更多
关键词 upper BOUND analysis velocity field ULTIMATE bearing capacity RECTANGULAR FOOTING ABAQUS
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A characteristic study of humic acids isolated from Arctic fjord sediments 预览
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作者 Jennees MATHEW Aswathy SHAJI +3 位作者 Anu GOPINATH Kottekkattu Padinchati KRISHNAN Sanil Vadakkan LOUIS Anoop Pullarkkat PRADEEP 《极地科学进展:英文版》 CSCD 2019年第1期24-34,共11页
Humic substances are ubiquitous natural materials found in sediments as a product of biochemical transformation reactions representing a significant proportion of organic carbon cycle on earth. This study involves the... Humic substances are ubiquitous natural materials found in sediments as a product of biochemical transformation reactions representing a significant proportion of organic carbon cycle on earth. This study involves the analysis of humic substances with special emphasis on humic acids(HAs) in sediments collected from the Kongsfjorden System of Arctic region in June, 2017. The characterization of the isolated HAs were done using various spectroscopic techniques viz. UV-visible, Fluorescence, FTIR and NMR. Isolated HAs were also undergone for elemental analysis along with other characterization. The UV spectral analysis results with a lower E4/E6 ratio suggesting the presence of HAs with high degree of aromaticity and condensation. Indications for the presence of hydroxyl, methyl, methylene, carbonyl, carboxyl, phenol, alcohol and amide groups were obtained from the FTIR spectrums of HAs. NMR spectral characteristics also confirm the presence of OH group as well as the presence of CH protons adjacent to C=X, were X can be any electronegative element. This also confirms the presence of carbonyl group which is also evident in the FTIR spectral studies. Presence of aliphatic regions slightly more dominated with long chain and/or alicyclic moieties rather than methyl groups was also inferred from the results of NMR. 展开更多
关键词 KONGSFJORDEN SEDIMENTS HUMIC ACIDS
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Seasonal and Interannual Variability of Bering Strait Throughflow from AO-FVCOM and Observation 预览
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作者 DENG Yongfei GAO Guoping +1 位作者 ZHANG Yu CHEN Changsheng 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第3期615-625,共11页
A high-resolution Arctic Ocean-Finite Volume Community Ocean Model(AO-FVCOM) and observational current data from 14 mooring stations in Bering Strait and surrounding regions between 1990 and 2015 were used to study th... A high-resolution Arctic Ocean-Finite Volume Community Ocean Model(AO-FVCOM) and observational current data from 14 mooring stations in Bering Strait and surrounding regions between 1990 and 2015 were used to study the seasonal and interannual variability of Bering Strait throughflow(BST). AO-FVCOM represented the BST with a climatological northward flux of 1.06 Sv, which was close to the observational mean of 0.94 ± 0.26 Sv. From the model results, the strongest volume flux was in summer, approximately 45% larger than that in winter. Interannual variability of BST was also indicated in the model results, and the maximum and minimum annual mean transports are in 2007 and 2012, respectively. AO-FVCOM showed larger differences from the observations in 2000, 2002, and 2015 than in other years, which may be related to the limitation of atmospheric forcing for the model. According to the driving mechanisms of BST, sea level difference(SLD) across the strait dominates the northward volume transport, and local wind is also important in forcing the seasonal variability of the BST and SLD patterns to change the BST indirectly. 展开更多
关键词 AO-FVCOM BERING STRAIT THROUGHFLOW seasonal and interannual variability in-situ OBSERVATION local wind sea level difference
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Spatial-temporal variability of submesoscale currents in the South China Sea 预览
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作者 LI Jianing DONG Jihai +1 位作者 YANG Qingxuan ZHANG Xu 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第2期474-485,共12页
Spatial and seasonal variabilities of submesoscale currents in the northeastern South China Sea are investigated by employing a numerical simulation with a horizontal resolution of 1km. The results suggest that submes... Spatial and seasonal variabilities of submesoscale currents in the northeastern South China Sea are investigated by employing a numerical simulation with a horizontal resolution of 1km. The results suggest that submesoscale currents are widespread in the surface mixed layer mainly due to the mixed layer instabilities and frontogenesis. In horizontal, submesoscale currents are generally more active in the north than those in the south, since that active eddies, especially cyclonic eddies, mainly occur in the northern area. Specifically, submesoscale currents are highly intensified in the east of Dongsha Island and south of Taiwan Island. In temporal sense, submesoscale currents are more active in winter than those in summer, since the mixed layer is thicker and more unstable in the winter. The parameterization developed by Fox-Kemper et al. is examined in terms of vertical velocity, and the results suggest that it could reproduce the vertical velocity if mixed layer instability dominates there. This study improves our understanding of the submesoscale dynamics in the South China Sea. 展开更多
关键词 submesoscale CURRENTS spatial-seasonal VARIABILITY SOUTH China Sea (SCS)
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Cyclin Cyc2p is required for micronuclear bouquet formation in Tetrahymena thermophila
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作者 Jing Xu Xiaoxiong Li +2 位作者 Weibo Song Wei Wang Shan Gao 《中国科学:生命科学英文版》 SCIE CAS CSCD 2019年第5期668-680,共13页
Meiotic bouquet formation(known as crescent formation in Tetrahymena thermophila) is indispensable for homologous pairing and recombination, but the regulatory mechanism of bouquet formation remains largely unknown. A... Meiotic bouquet formation(known as crescent formation in Tetrahymena thermophila) is indispensable for homologous pairing and recombination, but the regulatory mechanism of bouquet formation remains largely unknown. As a conjugation specific cyclin gene, CYC2 knockout mutants failed to form an elongated crescent structure and aborted meiosis progress in T. thermophila. γ-H2 A.X staining revealed fewer micronuclear DNA double-strand breaks(DSBs) in cyc2Δ cells than in wild-type cells. Furthermore, cyc2Δ cells still failed to form a crescent structure even though DSBs were induced by exogenous agents,indicating that a lack of DSBs was not completely responsible for failure to enter the crescent stage. Tubulin staining showed that impaired perinuclear microtubule structure may contribute to the blockage in micronuclear elongation. At the same time,expression of microtubule-associated kinesin genes, KIN11 and KIN141, was significantly downregulated in cyc2Δ cells.Moreover, micronuclear specific accumulation of heterochromatin marker trimethylated H3 K23 abnormally increased in the cyc2Δ mutants. Together, these results show that cyclin Cyc2 p is required for micronuclear bouquet formation via controlling microtubule-directed nuclear elongation in Tetrahymena. 展开更多
关键词 TETRAHYMENA MEIOSIS CYCLIN Cyc2p bouquet FORMATION
Towards reliable Arctic sea ice prediction using multivariate data assimilation
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作者 Jiping Liu Zhiqiang Chen +11 位作者 Yongyun Hu Yuanyuan Zhang Yifan Ding Xiao Cheng Qinghua Yang Lars Nerger Gunnar Spreen Radley Horton Jun Inoue Chaoyuan Yang Ming Li Mirong Song 《科学通报:英文版》 SCIE EI CSCD 2019年第1期63-72,共10页
Rapid declines in Arctic sea ice have captured attention and pose significant challenges to a variety of stakeholders.There is a rising demand for Arctic sea ice prediction at daily to seasonal time scales,which is pa... Rapid declines in Arctic sea ice have captured attention and pose significant challenges to a variety of stakeholders.There is a rising demand for Arctic sea ice prediction at daily to seasonal time scales,which is partly a sea ice initial condition problem,Thus,a multivariate data assimilation that integrates sea ice observations to generate realistic and skillful model initialization is needed to improve predictive skill of Arctic sea ice.Sea ice data assimilation is a relatively new research area,In this review paper,we focus on two challenges for implementing multivariate data assimilation systems for sea ice forecast,First,to address the challenge of limited spatiotemporal coverage and large uncertainties of observations,we discuss sea ice parameters derived from satellite remote sensing that (1)have been utilized for improved model initialization,including concentration,thickness and drift,and (2)are currently under develop- ment with the potential for enhancing the predictability of Arctic sea ice,including melt ponds and sea ice leads.Second,to strive to generate the "best"estimate of sea ice initial conditions by combining model simulations]forecasts and observations,we review capabilities and limitations of different data assimilation techniques that have been developed and used to assimilate observed sea ice parameters in dynamical models. 展开更多
关键词 ARCTIC sea ice PREDICTION Remote sensing Data ASSIMILATION
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